Fire-box sheet.



No. 736,693. PATENTBD AUG. 18, 1903'. J. CONROY.

FIRE BOX SHEET.

APPLICATION FILED JAN 15, 1901. N0 MODEL.

JZ WQWWM I FER g v rates Patented August 18, 1903.

FIRE-BOX SHEET.

SPECIFICATION forming part of Letters Patent No. 73 6,693, dated August18, 1903.

Application filed January 15,1901.

TO (1.56 lull/0m it may concern.-

Be it known that I, JAMES CONROY, residing at Salt Lake City, in thecounty of Salt Lake and State of Utah, have invented certain usefulImprovements in Fire-Box Sheets for L0- comotive and other SteamBoilers; and I do hereby declare that the following is a full, clear,and exact description of the invention, such as will enable othersskilled in the art to which it appertains to make and use the same,reference being had to the accompanying drawings, which form a part ofthis specification.

This invention relates to a fire-box sheet for locomotive and othersteam boilers.

The object of my invention is to provide a fire-box sheet so arrangedthat the sheet in expanding under heat and pressure will pinch thestay-bolts, so as to insure a tighter fitting the greater the heat andpressure.

In the accompanying drawings I have shown in Figure 1 a broken centralsectional view of a portion of a fire-box sheet embodying my invention.Fig. 2 shows a central sectional view with portions removed on lines a:a; in Fig. 3. Fig. 3 shows a front view of a broken portion of afire-box sheet embodying my invention, while Fig. 4 shows a sectionalview with portions broken away on line Y Y, Fig. 3.

All those familiar with this art of course understand as usuallyconstructed the staybolts, especially in the fire-box sheet oflocomotives, become leaky under the tension and strain incident to theoperation of the boiler.

As ordinarily constructed the fire-box sheet under strain is adapted towork away from the stay-bolts, so that in a short time a watertightconnection between the bolt and sheet is a thing of the past. In myinvention I overcome and prevent leakage by way of the stay-boltopenings in so embossing the plate and finally so positioning thestay-bolts within the embossed plates that as the sheet expands it ismade to bind tighter and tighter against the stay-bolts. In carrying outthis aim I provide the fire-box sheet B with a plurality of dishedindentations, or what are known in the art bumplets. These indentationsare preferably circular and are placed in series, preferably in astraight line, as is shown in Fig. 1, in which I have shown (No model.)

a number of dished indentations 1 1, which project in one direction andare upon that side of the sheet which comes outside or adjacent thefire. The next series of indentations 2 are pressed or upset in anopposite direction, asis shown in Fig. 2, for instance, theseindentations coining upon the inside of the boiler, the next series inturn again being dished or set outward, and so on.- Now where thestay-bolts are secured to the sheet the openings for the same are placedwithin those indentations which are outwardly bulged, these indentationsbeing threaded and being adapted to receive the stay-bolt C, as is shownmore particularly in Fig. 1, where A represents the opposite side of theboiler. From this it will be understood that I provide a fire-box sheetprovided with a plurality of bumplets or indentations alternatelyextending in 0pposite directions. Now as the steam-pressure and heatraise the area of the plate 13 there is a tendency of this plate B tobuckle, and this buckling will be outward against the heads 3 of thestay-bolt O, which are secured within the outwardly-bulged bumplets 1.This pressure would be inward as much as outward if it were not for thesteam-pressure within the boiler, which exerts a lateral force to drivethe expanding fire-box plates out ward. Now as the plate expands it actsin the form of a multiplicity of levers of the first order, each systemof levers finding a fulcrum at one of the stay-bolt heads, so that themetal surrounding these stay-bolt heads is forced under great pressureagainst the same, so that the greater the pressure or, in other words,the greater the'expansion of the metal between two stay-bolts thetighter will the stay-bolt heads be pinched within the sheet.

In referring to Fig. 2, for instance, were the stay-bolt heads placedwithin the bumplets or indentations 2 2 the plate as it expanded wouldbe forced away from the boltheads, and so the greater the pressurewithin the boiler the greater the likelihood of a leak between thebolt-head and the plate, which in its normal condition was continuallyworking away from the bolt-head, so that it would only be a question oftime before there would be a leakage. From this it will be noticed thatit is essential to set the bolt-heads within the outwardly-dishedbumplets in order to bring about the desired result.

While my invention is especially adapted to be used in connection withfire-box sheets for locomotives, I do not Wish to be understood asconfining myself exclusively to sheets for this class of boilers, as thesame may be used in connection with any other class of boilers wherestay-bolts are used under simi- IO lar conditions.

Having thus described my said invention,

what-I claim as new, and desire to secure by United States LettersPatent, is-

A fire-box sheet, provided with a plurality of inwardly and outwardlyextending dished indentations, all of said outwardly-dished indentationsbeing perforated and threaded as set forth.

JAMES CONROY. In presence of WM. R. HALL, C. M. DUNLOP.

